PICA::Modification::Queue implements a collection of modifications (PICA::Modification) or requests (PICA::Modification::Request) on PICA+ records together with the CRUDL operations get, insert, update, delete, and list. A queue may support insertion of modifications which then are stored as modification requests.

The default implementation is a in-memory (non-persistent) hash (PICA::Modification::Queue::Hash). Additional types of queues can be implemented in the PICA::Modification::Queue:: module namespace.